Posture-dependent Human 3He Lung Imaging in an Open-access MRI System

Tsai, Leo L.; Mair, R. W.; Li, Chih‐Hao; Rosen, Matthew S.; Patz, Samuel; Walsworth, Ronald L.

doi:10.1016/j.acra.2007.10.010

Cited by 18 publications

(13 citation statements)

References 77 publications

(159 reference statements)

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“…All participants (HV and ADDT) were only in the supine position for up to 20 min at a time during scanning and were upright between 129 Xe scans. Participants were encouraged to sit up and walk around between acquisitions and polarized xenon collections (~20 min) because previous studies confirmed that lung imaging results might not be a physiologically relevant after spending relatively long time in supine position . Therefore, we had to remove the patient from the scanner after each xenon dose or scan and relocalize (proton scan) the patient for the next xenon scan.…”

Section: Methodsmentioning

confidence: 99%

“…Participants were encouraged to sit up and walk around between acquisitions and polarized xenon collections (~20 min) because previous studies confirmed that lung imaging results might not be a physiologically relevant after spending relatively long time in supine position. 25,26 Therefore, we had to remove the patient from the scanner after each xenon dose or scan and relocalize (proton scan) the patient for the next xenon scan. Such approach likely led to a slight slice mismatch and potentially slight lung volume mismatch between the different xenon scans.…”

Section: Xe Mrimentioning

confidence: 99%

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Accelerated ¹²⁹Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha‐1 antitrypsin deficiency

Ouriadov

Guo

McCormack

et al. 2019

Magnetic Resonance in Med

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Purpose Multi‐b diffusion‐weighted hyperpolarized inhaled‐gas MRI provides imaging biomarkers of terminal airspace enlargement including ADC and mean linear intercept (Lm), but clinical translation has been limited because image acquisition requires relatively long or multiple breath‐holds that are not well‐tolerated by patients. Therefore, we aimed to accelerate single breath‐hold 3D multi‐b diffusion‐weighted 129Xe MRI, using k‐space undersampling in imaging direction using a different undersampling pattern for different b‐values combined with the stretched exponential model to generate maps of ventilation, apparent transverse relaxation time constant (T2∗), ADC, and Lm values in a single, short breath‐hold; accelerated and non‐accelerated measurements were directly compared. Methods We evaluated multi‐b (0, 12, 20, 30, and 45.5 s/cm2) diffusion‐weighted 129Xe T2∗/ADC/morphometry estimates using acceleration factor (AF = 1 and 7) and multi‐breath sampling in 3 volunteers (HV), and 6 participants with alpha‐1 antitrypsin deficiency (AATD). Results For the HV subgroup, mean differences of 5%, 2%, and 8% were observed between fully sampled and undersampled k‐space for ADC, Lm, and T2∗ values, respectively. For the AATD subgroup, mean differences were 9%, 6%, and 12% between fully sampled and undersampled k‐space for ADC, Lm and T2∗ values, respectively. Although mean differences of 1% and 4.5% were observed between accelerated and multi‐breath sampled ADC and Lm values, respectively, mean ADC/Lm estimates were not significantly different from corresponding mean ADCM/LmM or mean ADCA/LmA estimates (all P > 0.60 , A = undersampled and M = multi‐breath sampled). Conclusions Accelerated multi‐b diffusion‐weighted 129Xe MRI is feasible at AF = 7 for generating pulmonary ADC and Lm in AATD and normal lung.

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Section: Methodsmentioning

confidence: 99%

Section: Xe Mrimentioning

confidence: 99%

Accelerated ¹²⁹Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha‐1 antitrypsin deficiency

Ouriadov

Guo

McCormack

et al. 2019

Magnetic Resonance in Med

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show abstract

“…In-vivo 3 He MRI has been performed in human lungs at field strengths around 6 mT using homebuilt systems [39,17,16]. Our low-field system, which is designed to have very good field uniformity over a 5 Â 5 Â 5 cm volume, would be quite suitable for imaging rodent lungs.…”

Section: Advantages Of a Fully Phase-encoded Image Acquisitionmentioning

confidence: 99%

Very-low-field MRI of laser polarized xenon-129

Zheng

Cates

Tobias

et al. 2014

Journal of Magnetic Resonance

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“…O aprimoramento das pesquisas e a evolução tecnológica fizeram surgir novas preocupações, relacionadas às mudanças do comportamento humano e seus efeitos sobre seu organismo, tais como as doenças cardíacas, responsáveis por 30% do total de mortes no mundo (27), e a obesidade, relacionada com os novos hábitos alimentares dos indivíduos e o aumento do sedentarismo da população em geral (25). Os efeitos da posição corporal na distribuição regional da ventilação/ perfusão motivaram pesquisas recentes, em especial pelas questões que envolvem o cuidado e a sobrevida de indivíduos com doenças pulmonares restritivas e obstrutivas (28).…”

Section: Revisão Histórica Dos Estudos Sobre a Função Respiratória E unclassified

Influência das variações da postura sentada na função respiratória: revisão de literatura

2011

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INTRODUÇÃO: Os efeitos da postura sobre a função respiratória têm motivado pesquisas com o objetivo de rastrear alterações nos mecanismos de adaptação à mudança da postura corporal. A importância desse conhecimento está em compreender como essas alterações podem interferir na função respiratória de indivíduos saudáveis e em condições especiais, como obesos e gestantes. OBJETIVO: Realizar uma revisão bibliográfica para descrever o conhecimento produzido sobre as alterações da função respiratória em diferentes posturas corporais, em especial na postura sentada. MÉTODOS: Foram definidos os conceitos-chave da pesquisa: postura, postura sentada, testes respiratórios e função respiratória ou pulmonar; em seguida determinou-se o período de pesquisa que envolveu os anos de 2000 a 2010 (inclusive) e as bases de dados pesquisadas: SciELO, PEDro, Cochrane e Pubmed. RESULTADO: Encontrou-se que as primeiras pesquisas sobre função respiratória enfocavam alterações encontradas em mudanças significativas da postura corporal, geralmente em indivíduos saudáveis. O aprimoramento científico permitiu a incorporação tecnológica aos métodos de avaliação da função respiratória. Nos estudos sobre postura sentada, observa-se que as alterações são significativas em indivíduos com doenças pulmonares, cardíacas e idosos, entre outros, e que, mesmo em indivíduos saudáveis, as alterações nos testes de função podem ultrapassar a variação dos valores considerados normais para uma dada posição. CONCLUSÃO: São necessários maiores estudos para determinar o momento em que essas alterações podem ser significativas em indivíduos saudáveis e quais as alternativas possíveis para minimizar esses efeitos.

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Posture-dependent Human 3He Lung Imaging in an Open-access MRI System

Abstract: Effects of posture variation are observed, including posture-related effects of the diaphragm and distension of the lungs while vertical.

Cited by 18 publications

References 77 publications

Accelerated ¹²⁹Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha‐1 antitrypsin deficiency

Accelerated ¹²⁹Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha‐1 antitrypsin deficiency

Very-low-field MRI of laser polarized xenon-129

Influência das variações da postura sentada na função respiratória: revisão de literatura

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Posture-dependent Human 3He Lung Imaging in an Open-access MRI System

Abstract: Effects of posture variation are observed, including posture-related effects of the diaphragm and distension of the lungs while vertical.

Cited by 18 publications

References 77 publications

Accelerated 129Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha‐1 antitrypsin deficiency

Accelerated 129Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha‐1 antitrypsin deficiency

Very-low-field MRI of laser polarized xenon-129

Influência das variações da postura sentada na função respiratória: revisão de literatura

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Accelerated ¹²⁹Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha‐1 antitrypsin deficiency

Accelerated ¹²⁹Xe MRI morphometry of terminal airspace enlargement: Feasibility in volunteers and those with alpha‐1 antitrypsin deficiency